In recent years, a copper wire has been proposed as a bonding wire in place of a gold wire.
In general, copper as a raw material for a copper wire is refined by removing impurities and is used. However, in such high purity copper, there is a problem that the copper becomes easily oxidized when the copper is processed into a wire, or after the copper is processed into a copper wire. Therefore, bonding using a copper wire is likely to cause a defect, and particularly, the performance of the wire is likely to be degraded when the wire is stored at a high temperature.
As a technique using copper wire bonding, for example, there is disclosed a technique in Patent Document 1.
In Patent Document 1, there is disclosed a semiconductor device in which a copper-aluminum intermetallic compound is formed at a junction interface between a wire and an electrode in a semiconductor device in which an electrode and a lead of a semiconductor element are connected by a copper bonding wire, and led out. According to Patent Document 1, since a copper ball comes into close contact with the electrode by forming a CuAl2 layer at a junction interface between the copper ball and the aluminum electrode, the reliability is improved from the viewpoint of corrosion resistance.